package and2.ex.api.request;

public class BasicAuth {
		 private BasicAuth() {}

		    // conversion table
		    private static byte[] cvtTable = {
		        (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E',
		        (byte)'F', (byte)'G', (byte)'H', (byte)'I', (byte)'J',
		        (byte)'K', (byte)'L', (byte)'M', (byte)'N', (byte)'O',
		        (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T',
		        (byte)'U', (byte)'V', (byte)'W', (byte)'X', (byte)'Y',
		        (byte)'Z',
		        (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e',
		        (byte)'f', (byte)'g', (byte)'h', (byte)'i', (byte)'j',
		        (byte)'k', (byte)'l', (byte)'m', (byte)'n', (byte)'o',
		        (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t',
		        (byte)'u', (byte)'v', (byte)'w', (byte)'x', (byte)'y',
		        (byte)'z',
		        (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4',
		        (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9',
		        (byte)'+', (byte)'/'
		    };

		    /**
		     * Encode a name/password pair appropriate to
		     * use in an HTTP header for Basic Authentication.
		     *    name     the user's name
		     *    passwd   the user's password
		     *    returns  String   the base64 encoded name:password
		     */
		   public static String encode(String name,
		                         String passwd) {
		        byte input[] = (name + ":" + passwd).getBytes();
		        byte[] output = new byte[((input.length / 3) + 1) * 4];
		        int ridx = 0;
		        int chunk = 0;

		        /**
		         * Loop through input with 3-byte stride. For
		         * each 'chunk' of 3-bytes, create a 24-bit
		         * value, then extract four 6-bit indices.
		         * Use these indices to extract the base-64
		         * encoding for this 6-bit 'character'
		         */
		        for (int i = 0; i < input.length; i += 3) {
		            int left = input.length - i;

		            // have at least three bytes of data left
		            if (left > 2) {
		                chunk = (input[i] << 16)|
		                        (input[i + 1] << 8) |
		                         input[i + 2];
		                output[ridx++] = cvtTable[(chunk&0xFC0000)>>18];
		                output[ridx++] = cvtTable[(chunk&0x3F000) >>12];
		                output[ridx++] = cvtTable[(chunk&0xFC0)   >> 6];
		                output[ridx++] = cvtTable[(chunk&0x3F)];
		            } else if (left == 2) {
		                // down to 2 bytes. pad with 1 '='
		                chunk = (input[i] << 16) |
		                        (input[i + 1] << 8);
		                output[ridx++] = cvtTable[(chunk&0xFC0000)>>18];
		                output[ridx++] = cvtTable[(chunk&0x3F000) >>12];
		                output[ridx++] = cvtTable[(chunk&0xFC0)   >> 6];
		                output[ridx++] = '=';
		            } else {
		                // down to 1 byte. pad with 2 '='
		                chunk = input[i] << 16;
		                output[ridx++] = cvtTable[(chunk&0xFC0000)>>18];
		                output[ridx++] = cvtTable[(chunk&0x3F000) >>12];
		                output[ridx++] = '=';
		                output[ridx++] = '=';
		            }
		        }
		        return new String(output);
		    }


}
